Right now I think 2/3/5 plexes look most interesting to me, but I'm open to having my opinion changed and horizon expanded.

Glad to hear the younger folks expanding their minds and horizons.

Is there a way you could easily dump it at that point?

Even a newer 90s home you should easily be under 10k unless its a private home on land. 

On the one hand managing 5  or 6 properties is the sweet spot for being able to qualify for all things residential and is easily doable for a busy person; on the other hand it is becoming tougher because you don't have the benefits of scale where the income becomes more significant and helps you through a vacancy or 2.

These units have been very good for me and I am looking to expand and find some more deals.

This technique is called pipe bursting where a new pipe is underwater in place and as the machine pulls the new pipe it also expands the old pipe out of the way.

A foundation issue is usually fairly easily taken care of and if planned for in the renovation process and purchase price of the home, can still be lucrative.  

Some of them you need to look past the current price and rent to see the potential rent that it could get to easily, others you have to know the situation of the seller to see how much lower than asking they will probably accept.  

An RV can be easily moved if need be compared to a mobile home.Thanks in advance to everyone.Mark